During medical treatment, patients often require medication, blood, or fluids. The most efficient way of administering these substances is by depositing them directly into the patient's blood stream where the circulatory system quickly directs the substance to the target tissue or organ. Administering a substance directly into a patient's blood stream is most commonly accomplished by injection with a conventional needle and syringe. During the course of treatment, however, a patient will often require repeated or continuous doses of medications. It will be appreciated that repeated injections with conventional syringes can damage blood vessels and cause significant discomfort to the patient.
Therefore, when a patient requires repeated doses of medication or other substances, catheters are commonly used in the health care profession. In one common configuration, a catheter comprises a catheter adaptor and a hollow tubular cannula. The catheter adaptor and the catheter cannula are attached end-to-end. The catheter adaptor and cannula are usually constructed from a single mold such that a continuous fluid flow opening extends from the catheter adaptor to the catheter cannula. When the catheter is in use, the hollow tubular cannula is partially inserted into the patient's blood vessel, while the catheter adaptor remains outside where it can be accessed by medical personnel. A medication container is securely attached to the catheter adaptor. The medication flows through the catheter adaptor and cannula via the continuous fluid flow opening and directly into the patient's blood vessel. As such, the patient receives a continuous supply of medication without repeated injections with conventional needles and syringes.
Typically, a vascular access device is used to insert a catheter within a patient's blood vessel. A vascular access device generally comprises a housing, an introducer needle, and a catheter. The housing is used to grip the vascular access device during catheter insertion. The introducer needle is attached to the end of the housing and used to pierce the patient's skin and access the blood vessel. The catheter fits concentrically over the introducer needle and is held in place by friction engagement between a catheter adaptor and the housing. The relative lengths of the introducer needle and the catheter cannula are such that the tip of the introducer needle extends beyond the end of the catheter cannula when the catheter adaptor is attached to the housing.
In use, a clinician pierces the patient's skin with the introducer needle and locates the patient's blood vessel. Once the introducer needle is inserted into the patient's blood vessel, the patient's blood pressure causes blood to flow into the introducer needle. This "flashback" blood is allowed to exit into a chamber positioned within the housing. The chamber and housing are usually made of a clear or opaque material so that the clinician can see the flashback blood entering the chamber. Flashback blood in the chamber alerts the clinician that the blood vessel has been successfully punctured. With the introducer needle in the patient's blood vessel, the clinician detaches the catheter adaptor from the housing. The catheter cannula is then inserted into the patient's blood vessel by sliding the catheter cannula along the introducer needle until the desired length of the cannula is within the blood vessel. While holding the catheter in place, the introducer needle is removed by slowing pulling back on the housing leaving the catheter cannula within the patient's blood vessel.
It will be appreciated that the introducer needle is contaminated with the patient's blood and any blood borne diseases, such as HIV and hepatitis, the patient may carry. Exposed introducer needles, therefore, pose a health hazard to clinicians and other patients. To lessen the risk of accidental needle punctures or blood exposure, some vascular access devises are designed with spring retracting needles. Once the cannula is positioned within the patient's blood vessel, the clinician disengages a locking mechanism thus allowing the spring to propel the needle into the housing of the vascular access device. The housing completely encloses the needle, protecting the clinician from accidental needle punctures.
While spring retracted needle designs significantly cut down on accidental needle punctures, some improvements to the designs could be made. It will be appreciated that as the needle retracts, some blood will adhere to the needle through normal surface tension. Usually, this small amount of blood does not pose a threat to clinicians because it becomes enclosed by the housing. If the needle retracts too fast, however, blood on the needle may break the surface tension and splatter or drip on the patient or clinician. The potentially contaminated blood posses a serious health threat to the clinician and other medical personnel.
From the foregoing, it will be appreciated that it would be an advancement in the art to provide devices for slowing down or dampening the velocity of the needle as it retracts into the housing of the vascular access device.
It would also be an advancement if the dampening devices prevented blood from splattering or dripping during needle retraction.
It would be yet another advancement in the art if the dampening devices could be regulated to provide different degrees of dampening.
It would be a further advancement in the art if existing vascular access devices could be retrofit with the dampening devices.
Such dampening devices and methods are disclosed and claimed herein.